How Well Do Cordless Impact Guns Work?

Tools are like toys for us semi-grown hot rodders. There are a lot of them we have to have, and more we would love to own. If time is not an issue, the work you’d do with a cordless impact wrench can be done with other tools, including a breaker bar, a ratchet, or a pneumatic impact wrench where air lines are available. A cordless impact gun is a perfect example of a tool that will make your life easier but isn’t an absolute necessity.

But you still want one, right?

Impact guns use hammers that beat against a plate inside the tool to cause the bit to rotate. How many times it hits per minute and how hard it hits all depend on the manufacturer. The battery life, whether it is nickel-cadmium or the more expensive lithium-ion, also factors into a gun’s performance. We grabbed four basic models from different manufacturers to see how they stack up against each other in terms of battery life, user friendliness, and overall strength.

2/5

Snap-on

Height

10 5⁄8 inches

Width

2 3⁄4 inches

Length

9 7⁄8 inches

Weight

7.55 pounds

Max. Load Tension

25,000–25,500 pounds

Breakaway

255 lb-ft

Break-loose

189 lb-ft

Voltage

18V

Max. Torque

400 lb-ft

No Load Speed

0–2,200 rpm

Warranty

One year tool & charger/one year battery

Impacts Per Minute

2,100

Charge Time

40 minutes

Part Number

CT6850

Price

$570.00

*Pros: Powerful; Cons: Price

The Stuff

While most of the standard kits we chose each came with two nickel-cadmium (NiCd ) batteries (apart from Harbor Freight, which had one), most of these manufacturers offer lithium-ion batteries that will work with the same guns for a $100 or more up-charge. Only Snap-on offers a lithium-ion option that requires a separate gun. Harbor Freight’s brand, Chicago Electric Power Tools, was the least expensive (PN 67845, $139.99) and came with a small attachable battery charger and case. Craftsman comes in Second in the price war but is smallest in size (PN 17339, $169.99). It included a charging stand, a hard case, a 2-inch extension, and a built-in LED light. Kobalt currently offers only a lithium-ion version (PN 325931, $269.99), which we tested with a NiCd battery (PN 5667, $41.97). The kit included a large, slow charger stand (that beeped when charged), a built-in LED light, and a hard case. The Snap-on tool was the most expensive but nicest looking (PN CT6850, $570.00). It included a charging stand with charge capacity lights and a case.

3/5

Craftsman

Height

10 1⁄8 inches

Width

3 inches

Length

8 1⁄2 inches

Weight

5.7 pounds

Max. Load Tension

21,000–21,000 pounds

Breakaway

171.7 lb-ft

Break-loose

153 lb-ft

Voltage

19.2V

Max. Torque

200 lb-ft

No Load Speed

3,000 rpm

Warranty

One year limited

Impacts Per Minute

3,000

Charge Time

30 minutes

Part Number

17339

Price

$169.99

*Pros: Tiny and competes with others; Cons: Quick drop off in max. torque after use

The Test

We wanted to see how long each gun would produce absolute maximum tightening torque before weakening and dying. We tightened individual lug nuts onto wheel studs on a Summit Racing wheel adapter (PN TRD-7069), which we bolted to a junk wheel. Beginning with the nuts finger tight, we tightened 20 of them to the gun’s relative maximum (running the gun for 3–5 seconds) and used a Snap-on digital torque wrench to give us the loosening torque of every lug. We observed how long each gun worked only using its full torque strength.

After testing battery life, we headed to ARP’s Research and Development center in Ventura, California, to test maximum one-time torque with a fully charged battery. Using a Skidmore-Wilhelm Hydraulic Load Cell, we operated each gun for 20 seconds nonstop on an eight-point ARP nut screwed onto a 5⁄8-inch wheel stud, paused for one minute, and then tightened for another 10 seconds. The load cell is read in pounds-tension, which is related to torque, but too many other factors (mainly lubricant) caused that correlation to be inexact. So we used a Snap-on 1⁄2-inch-drive air impact gun for a reference point.

4/5

Kobalt

Height

11 inches

Width

3 inches

Length

10 1⁄4 inches

Weight

7.75 pounds

Max. Load Tension

16,000–17,000 pounds

Breakaway

147 lb-ft

Break-loose

123.5 lb-ft

Voltage

18V

Max. Torque

300 lb-ft

No Load Speed

0–1,900 rpm

Warranty

Five years tool/Three years battery

Impacts Per Minute

2,100

Charge Time

30 minutes

Part Number

325931

Price

$269.99 (lithium-ion)

*Pros: Comfortable, long warranty; Cons: Didn’t last as long

After running the nut down on the load cell, we used a Snap-on digital torque wrench to record the breakaway torque (the maximum force it takes to start to turn the bolt or nut tighter), and then loosened the nut to record the maximum loosening torque. The nut’s actual torque falls somewhere in between the two figures, which (unless you are NASA) was the best way to gauge the nut’s actual torque.

The Results

An air-fed impact gun only works as well as the air supply, but maximum load from our reference Snap-on wrench was 25,500 to 26,000 pounds-tension, breakaway torque was 254 lb-ft, and break-loose torque was 192 lb-ft. Those figures were nearly the same as the Snap-on cordless impact gun. At full strength, the Snap-on gun tightened 104 lugs, and its torque stayed higher for a longer period of time than that on the other guns. The Harbor Freight wrench lasted the longest (with 108 pulls), but torque slowly fell off after 80 pulls. The Craftsman gun made 75 pulls, and the Kobalt gun lasted a little longer than 50.

5/5

Harbor Freight

Height

10 3⁄8 inches

Width

3 1⁄8 inches

Length

8 7⁄8 inches

Weight

5.95 pounds

Max. Load Tension

15,000–16,000 pounds

Breakaway

157 lb-ft

Break-loose

115 lb-ft

Voltage

18V

Max. Torque

211 lb-ft

No Load Speed

0–2,100 rpm

Warranty

90 days

Impacts Per Minute

3,000

Charge Time

2 1⁄2 hours

Part Number

67845

Price

$139.99

*Pros: Prowerful for the price; Cons: Feels cheap

Conclusions

From a purely performance standpoint, the Snap-on wrench won this contest, but it also costs almost three times as much as some of its competitors. It, and the Kobalt gun, were larger than the others and more comfortable in our hands. They didn’t shake the fillings in our teeth loose when using them. But the Craftsman gun’s small size would make a big difference in tight spaces—at a junkyard, say, where air lines aren’t accessible. The surprise here was the Harbor Freight wrench. It’s the cheapest, and felt that way in our hands, but it proved to be a strong performer.

Bottom Line

If you have the dough, go with the Snap-on. If not, any will work. Each gun can fit a certain need. The Craftsman is the smallest, the Kobalt a good buy, and the Harbor Freight a surprising competitor for the cheap price.